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RAID 5

Definition - What does RAID 5 mean?

RAID 5 is a standard RAID level configuration that uses block-level data striping and distributes parity to all the disks. There is still some overhead during parity calculations, but since parity is written to all disks, no single drive can be considered the bottleneck, and I/O operations are spread evenly across all drives. RAID 5 outperforms RAID 4 and achieved popularity because of the low cost of redundancy it provides.

Techopedia explains RAID 5

Because RAID 5 stripes data and parity bits across all disks, it is very tolerant of single disk failures, although this reduces the disk capacity slightly. If a disk fails, it simply has to be replaced and the system can go on. Further data reads are calculated from the parity so that end users do not even notice the disk failure.

RAID 5 is similar to RAID 4, but the dedicated drive used for parity was removed and replaced with a distributed algorithm. This resolves the bottlenecks caused by a dedicated parity disk.

Advantages:

  • Can tolerate the loss of a single drive
  • Good random read performance
  • Good sequential read and write performance

Disadvantages:

  • Parity calculation may slow down system
  • Due to parity overhead, random write performance takes a hit
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